Why Is D.c.'s Official Weather Measured In Virginia? (Transcript) | WAMU 88.5 - American University Radio

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Why Are D.C.'s Official Weather Readings Measured in Virginia?

MS. REBECCA SHEIR

00:00:08
Welcome to "Metro Connection." I'm Rebecca Sheir and it's hard to believe, but in just about a week we'll be halfway through summer. Yeah, time flies, right? So before we lose our chance, today we're bringing you a show we do every year, our annual celebration of all things summer in the city. We call it "Feeling the Heat."

MS. REBECCA SHEIR

00:00:32
We'll visit one of D.C.'s heat islands and learn what's being done to cool things off when the sun beats down. We'll meet farmers trying to make their gardens grow, even when our weather is all over the map. And we'll experience some culinary heat, at a restaurant that takes spice to a whole new level.

MS. REBECCA SHEIR

00:00:56
But first, even though we're calling today's show "Feeling the Heat," it's been relatively cooler this past week. Less humid, too. But if you rewind two years back to a particular day in Juneā€¦

MR. PAT BROGAN

00:01:06
I'm Pat Brogan, it's 4:04. 103 degrees now in Northwest Washington. A record high temperature for the D.C. region that stood for almost 80 years was broken today when the mercury reached 104 degrees at Reagan National Airport. The old record of 101 degrees was set in 1934.

SHEIR

00:01:25
That was WAMU news anchor extraordinaire, Pat Brogan, back on June 29, 2012, when records were being broken all over the place in terms of D.C.'s temperatures. Well, I say D.C.'s temperatures, but as we just heard the mercury wasn't actually being measured in D.C.

MR. JASON SAMENOW

00:01:41
Ideally, Washington, D.C.'s temperature reading would be taken in Washington, D.C. It wouldn't be surrounded by tarmacs. It wouldn't be adjacent to the river.

SHEIR

00:01:50
And yet, says Jason Samenow, weather editor for the Washington Post, it is. Since 1942 D.C.'s temperature sensors have been across the Potomac in Arlington, Va., at the airport now known as Ronald Reagan Washington National.

SAMENOW

00:02:04
Most weather stations across the country are co-located with airports. And that's because aviation needs reliable weather observations for pilots to know what the visibility is, what the cloud ceilings are to protect against aviation accidents.

SHEIR

00:02:18
Now, when I met up with Jason earlier this week it wasn't at DCA. Instead, we picked a spot that's been proffered as an alternate location for D.C.'s official weather gauge, the White House.

SAMENOW

00:02:29
Robert Leffler, who's this retired National Weather Service climatologist, he actually put out a proposal that the official weather observing station be at the White House. And that was actually floated around the National Weather Service for a period of time, but it was squashed. I think because they're being added costs to having a weather observer at the White House.

SHEIR

00:02:48
Plus, Jason says, moving the station could screw up decades of carefully kept temperature records.

SAMENOW

00:02:54
If you're trying to see whether the climate's changing over time, you don't know if it's due to the fact that the location's changed or whether there's actually a true climate change signal during that time period.

SHEIR

00:03:04
But still, Jason acknowledges a number of potential problems with the current observation spot for Washington's weather.

SAMENOW

00:03:09
Number one, it's in a very low elevation, being right along the riverbank. Number two, the river can actually influence the temperature at the airport. So you have wind from the South coming right up the river, that's going to influence the temperature because the water temperature of the river is going to influence the temperature of the air at the airport.

SAMENOW

00:03:27
And thirdly, you're in a very urbanized location with a lot of asphalt. You've got the runways there and the tarmac. And so that's going to also potentially influence the temperature reading that you're getting at the airport.

SHEIR

00:03:40
Hasn't it been shown that temperatures measured at DCA are often among the highest in the metro region? I mean, haven't we seen a number of days where the temperatures at the airport were measured to be way higher than they were at the National Weather Service's other observing sites in the region?

SAMENOW

00:03:53
That's exactly right. And Robert Leffler, who's a retired climatologist from the National Weather Service, who's looked at this data very closely and he's seen that Reagan National Airport is always up there, always at the top in terms of the temperature readings across the region. And even sometimes as hot as temperature regions to our south, like places like Richmond and Atlanta.

SAMENOW

00:04:12
Reagan National on some mornings is reading warmer than it is in Atlanta, just because there's all this asphalt surrounding it. There's a river. So the temperature has a hard time dropping off at night. However, if you're looking for a temperature reading which may be somewhat indicative of what it's like in downtown Washington, with a lot of concrete and asphalt, Reagan National Airport isn't the worst proxy for that.

SAMENOW

00:04:36
It's not a terrible representation of what the weather conditions are like in downtown Washington. Now, whether it's a good indicator of what the entire region's temperature is like, that's an entirely different story.

SHEIR

00:04:48
So where exactly is the weather gauge at the airport?

SAMENOW

00:04:51
Well, my understanding is that it's on a grassy area adjacent to the tarmac, but that the temperature reading is -- it's shaded. It's covered. It's in a shelter. So it's protected from some of the effects that you might have from the asphalt and whatnot. But it's not an ideal environment for recording temperatures.

SHEIR

00:05:11
So one last question -- and I'm actually posing this on behalf of my colleagues at WAMU -- so we have all these news anchors and they'll come on the air every few minutes and they'll give the time and temperature for D.C. I do it occasionally. Should we really be saying, you know, at 4:06 it's such and such temperature at Reagan National Airport, rather than it's such and such temperature in, say, Northwest D.C., Southwest D.C.?

SAMENOW

00:05:34
Yeah, if you're a purist you want to refer to the location at which the temperature's taken, which is Reagan National. But, again, I mean, if you talked to the weather observers at Reagan National, they'll tell you that the conditions there are pretty similar to what you're going to get in downtown Washington. So, again, as a proxy, if you want to generalize, you know, we're just talking about across the river here. So it's not a huge distance.

SAMENOW

00:05:55
And the microclimatic influence is not withstanding. So you're not committing a crime if you say that the temperature at Reagan National Airport is the temperature in D.C., because it's going to be pretty close in most situations.

SHEIR

00:06:07
So we're still being honest with our listeners. I guess I just want to make sure that we're telling them the truth, technically.

SAMENOW

00:06:13
Most of the time you're going to be pretty close.

SHEIR

00:06:22
That was Jason Samenow, weather editor for the Washington Post, outside the White House. And now we ask you, if you could take D.C.'s official temperature anywhere, anywhere at all, where would it be? Take our poll at metroconnection.org or tweet us your answer. Our handle is @wamumetro.
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